Process for the production of highquality heating oils



E. J. NlEHAus, JR., Erm.

Fneuay 5, 1949 Aug. 26, 1952 PROCESS FOR THE PRODUCTION OF HIGH-QUALITY HEATING OILS Patented Aug. 26, 1952 PROCESS FOR THE PRODUCTION OF HIGH- QUALITY HEATING OILS Edward J. Niehaus, Jr., and Hugh F. Whitney, Jr., Baltimore, Md., assignors to Standard Oil Development Company, a corporation of Delaware Application May 5, 1949, serial No. 91,514

(ci. 19a- 29) 3 Claims.

The present invention is concerned with the production of high quality petroleum oil products. The invention is more particularly concerned with the production of high quality `petroleum oil products boiling in the heating oil boiling range. In accordance with the present process, high quality heating oil products are produced by contacting virgin petroleum oil fractions under controlled conditions with a caustic solution and an oxygen-containing gas. l l

It is well known in the art to refine hydrocarbon fractions by various processes in order to remove `objectionable constituents therefrom. Thus, it is known to treat hydrocarbon fractions with chemical reagents such as sulfuric acid and caustic solutions in order to remove various sulfur compounds. It has also been suggested that hydrocarbon fractions be contacted with caustic such as a sodium hydroxide solution in the presencecf air or oxygen. However, in these processes wherein caustic and oxygenhave been utilized, it has not been practical due to emulsilication difliculties to employ relatively strong caustic solutions. Furthermore, the temperature of contact has likewise been limited. Due to these limitations, in order to secure a satisfactory low copper number the time of contact of necessity had to be relatively long.`

It has now been 1discovered that if the oil to be contacted,fparticularly if it be a virgin oil boiling in the heating oil boiling range is contacted in an initial stage with a relatively weak caustic solution, it is then possible to contact the same in a secondary stage with caustic solutions of a strength which have heretofore notbeen entirely practical due to emulsication difficulties and the like. Furthermore, by operating in accordance with the present invention it is possible to use a relatively high temperature in the secondary stage which will produce unexpected and desirable results. The process of the present invention` maybe readily understood by reference to the drawing illustrating one embodiment of the same.

Referring specifically to the drawing, a feed oil, which for` the purpose of illustration is assumed to be an uncracked petroleum fraction boiling in the range from about 350 F. to 700 F. is introduced into initial caustic treating zone I by means of feed line I. A relatively weak caustic solution having a concentration in the range from about 3 to 7 B. is introduced into zone III by means of line 2 and satisfactory mixing secured by means of orifice or equivalent mixers 8. For the purpose of illustration it is assumed that the caustic solution comprises a sodium hydroxide solution. Initial treating zone I0 may comprise any suitable number and arrangement of stages. The spent caustic solution is Withdrawn from zone I0 by means of line 3 while the treated oil is removed from zone I0 by meansof line 4 and introduced into secondary treating zone 20. A relatively strong caustic solution is introduced into zone 20 by means of line 5 andwithdrawn by means of line 6. In accordance with the process of the present invention air or oxygen, or other oxygen-containing gases are introduced :into the oil in line 4 by means of line 1 and satisfactolt mixing secured by means of orifice or equivalent mixers 38. Also, in accordance with the process of the present invention, `a relatively highftemperature is employed in zone 20 in conjunction with the relatively strong caustic solution. This may be secured by passing the feed stream through a heat exchanger or other equivalent means or by heating zone 2|] in any desirable manner. Treated oil ofrelatively high alkalinity is withdrawn from secondary treating zone 20 by means of line 9.

This stream is introduced into zone 30 wherein it is washed free of its alkalinity by water. The Water is introduced into line 9 `by means of line I I. The water and the oil are mixed by introducing the same through an orifice mixer 48 or equivalent means. A finished oil ,productl having a relatively low copper number and other satisfactory characteristics is withdrawn from zone 30 by means of line 3|. In accordance with the preferred adaptation of the present invention the spent Water having a relatively weak alkalinity withdrawn from zone 3i) is recycled to zone Iil by means of line I6, pump I5 and line 21. Fresh make up caustic may be introduced by means of line 32.

Recirculaticn of the caustic may also be employed With respect to zone 20. The spent caustic phase is withdrawn from zone 20 by means of line 5 and may be withdrawn from the system by means of line I4. However, it is preferred to recycle at least a portion of this caustic phase by means of pump 25 and line 5. Fresh make up caustic may be introduced by means of line Il.

The present invention is generally concerned with the treatment of virgin petroleum oil fractions boiling in the heating oil boiling range. It has been discovered that if the heating oil is treated in accordance with the present invention, it is possible to produce a satisfactory heating oil product without the necessity of a so-called, Doctor Treat. 1 By the elimination of the Doctor Treat not only is it possible to produce a maximum yield of heating oil product, but it is also possible to produce a very high quality heating oil product. This is extremely desirable since it is urgent that a maximum yield of high quality heating oils be produced.

In accordance with the process of the present invention, the petroleum fractions are contacted in an initial stage with a relatively dilute caustic solution, preferably with a sodium hydroxide solution.

The concentration of the caustic solution used in the initial stage should not be in excess of 8 to 10 B. and preferably should have a gravity of about 3 to 7 B. The concentration of the caustic solution utilized in the second stage should be one having a gravity not less than 40 B. and preferably should have a gravity in the range from 50 to 55 Be'. The temperature employed in the secondary stage should be not less than about 105 F., preferably above 130 F. Particularly desirable results are secured when the temperature employed in the secondary stage is in the range from about 140 F. to 160 F.

The amount of weak caustic employed in the y initial stage should be in. the range from about 0.5 to 5% by volume based upon the volume of oil being contacted. The amount used will depend upon the amount of hydrogen sulnde and organic acids present in the feed oil. y

The amountv of caustic utilized in the secondary stage is in the range from about .25% to 3% by volume of hydroxide solution per volume of oil contacted. In general it is preferred that the amount of sodium hydroxide or other alkali metal hydroxide solution used be in the range from .25% to 1% by volume per volume of oil contacted. It is believed that the strong caustic catalyzes the air oxidation of the mercaptans to disuldes. vIt is therefore desirable to secure excellent mixing of the strong caustic, the air and the oil being treated.

The process of the present invention may be more readily understood by reference to the following examples; illustrating embodiments of f the same.

EXAMPLE I Various operations were conducted using as a feed stock a virgin petroleum oil fraction boiling in the range from 350 F. to 670 F. The results of these operations are listed in Table I.

1 Doctor Sweetening Process-In this process the mercaptans are first converted to oil soluble lead mercaptrdes. This 1s effected by contacting the oil with doctor solution, .1. e., lead oxide dissolved in an aqueous caustic soda solution. The naphtha containing the lead mercaptnn has mgected into it a sulfur solution; the result being the conversion of the mercaptides to a disulfide, and the formation of insoluble lead sulfide.

4t Table IY OXYGEN AND AIR-STRONG CAUSTIC SWEETEING WEST TEXAS VIRGIN HEATING OIL From the above data it is apparent that excellent results are secured when a 50 B. solution is employed rather than a B. solution. It is also apparent that it is very desirable to employ a temperature in the range above about 105 F.

It is also evident from the above data that the rate of treating is tremendously increased when utilizing caustic soda having the strength of B. as compared toutilizing a soda having a strength of 40 B.

It is claimed:

1. Process for the preparation of an improved heating oil which comprises contacting a virgin petroleum oil boiling `in. the heating oil boiling range in an initial stage with a relatively weak sodium hydroxide solution having a gravity in the range from about 3 to 7 B., withdrawing the oil and mixing the same Vwith oxygen and a relatively strong sodium hydroxide solution having a gravity in the range from about 50 to B. in a secondary stage, maintaining the mixture at anelevated temperature in the range from about F. to 160 F.J separating the treated oil and removing the same from said secondary stage andcontacting the oil in a tertiary stage with Water, thereafter segregatng a high quality oil having a relatively low mere captan content.

2. Process as delned by claim 1 wherein the amount of caustic employed in the secondary stage is from .25 to 3% byvvolume based upon the volume of oil treated.

3. Process as defined by claim 2 wherein said temperature utilized in said secondary stage is in the range from about to 160 F.

f EDWARD J. NIEHAUS, JR.

HUGH F'. WHITNEY, JR.

REFERENCES CITED The following references are oi' record in the iile of this patent: Y

UNITED STATES PATENTS Number Name Bate 2,390,296 Gilbert- Y Dec. 4, 1945 2,413,945 Bolt Jan. 7, 1947 2,462,810 Ferguson Feb. 22, 1949 2,478,603 Stratton Aug. 9, 1949 2,488,000 Bernard Nov. 15, 1949 

1. PROCESS FOR THE PREPARATION OF AN IMPROVED HEATING OIL WHICH COMPRISES CONTACTING A VIRGIN PETROLEUM OIL BOILING IN THE HEATING OIL BOILING RANGE IN AN INITIAL STAGE WITH A RELATIVELY WEAK SODIUM HYDROXIDE SOLUTION HAVING A GRAVITY IN THE RANGE FROM ABOUT 3* TO 7* BE., WITHDRAWING THE OIL AND MIXING THE SAME WITH OXYGEN AND A RELATIVELY STRONG SODIUM HYDROXIDE SOLUTION HAVING A GRAVITY IN THE RANGE FROM ABOUT 50* TO 